This invention relates to apparatus and method for delivering signatures to a gatherer feed mechanism in a generally vertically stacked on-edge array. Feed hoppers are commonly provided to feed signatures to a feed drum of an inserter. In hoppers such as that described in U.S. Pat. No. 2,163,732 signatures are conveyed in a vertically stacked or on-edge array to a discharge area of the hopper. The signatures are extracted from the discharge area, opened and dropped on the saddles of a saddle conveyor chain. The signatures are conveyed to the discharge area between side walls which are spaced apart a distance less than the width of a signature so that a bow is formed in the signature by the side wall spacing. The bow assists in providing stability to the on-edge signatures.
Chronic difficulties with vertical feed hoppers such as that described in the aforementioned patent are in maintaining the bow in the signatures and in delivering the signature to the discharge station of the hopper in a controlled manner. For example, signatures tend to become skewed, that is, assume a full width diagonal attitude between the side walls. The skewed signatures are no longer stable and may fall or move into a non-vertical position so that they cannot be extracted correctly at the discharge area. Once the signatures become skewed they will remain in that condition up to the discharge area unless manually restored to the bowed condition. Constant attention must, therefore, be paid to each hopper to ensure that the signatures are properly fed to the discharge area. Since a multiplicity of hoppers are employed in a gathering operation, manual labor costs are significant.